почему-то не работает дешифровка
package com.javarush.task.task18.task1826;
import java.io.*;
/*
Шифровка
*/
public class Solution {
public static void main(String[] args) throws IOException {
String first = args[1];
String second = args[2];
BufferedInputStream input = new BufferedInputStream(new FileInputStream(first));
BufferedOutputStream output = new BufferedOutputStream(new FileOutputStream(second));
if (args[0].equals("-e")) {
int i;
while ((i = input.read()) != -1) {
output.write(input.read() + 1);
}
} else if (args[0].equals("-d")) {
int i;
while ((i = input.read()) != -1) {
output.write(input.read() - 1);
}
}
input.close();
output.close();
}
}